Friday, Sep 5, 2008
While other search engines sputter and fail, Monika Henzinger, Google's director of research, has an answer to every query.
Jun 21, 2001 | Visiting Google's Mountain View, Calif., headquarters is like taking a time machine to happier, fatter times. Think Silicon Valley in 1999, at the height of the dot-com boom.
The time warp starts before you enter the building. Part of the office's parking lot is cordoned off for twice-weekly rollerblade hockey games, complete with Google-supplied team jerseys. The lobby is decorated with a merry array of lava lamps and a piano at which stressed-out coders can knock off a few bars to decompress. At the company "cafe" -- never called a cafeteria -- employees eat free gourmet lunches styled by the Grateful Dead's former chef. And let's not forget the on-site masseuses.
There's a pool table, a Ping-Pong table, a Foosball table and a gym. And behind a love-bead curtain in the women's locker room is a sauna. It's a workaholic Californian approach to luxury -- bring the spa to work! -- although a company spokeswoman confides that she's never seen anyone actually use the sauna.
A goofy poster in the lobby has snapshots of employees using their entire bodies to spell out the words "Google World's Best Search Engine." They're all smiling, and it's not hard to see why. While others in Silicon Valley are grousing bitterly as they sip pink-colored drinks at increasingly pathetic pink-slip parties and while other search engines are desperately selling out their links to the highest bidder, Google is in the plum spot of providing search capabilities to Yahoo. All told, Google currently gets 100 million search queries a day.
Monika Henzinger, 35, director of research at Google, is driving the technical research to make those searches better. With her team of 10 computer scientists -- all men -- the German-born Ph.D. works on improving Google's search functionality and moving Google into new areas such as mobile phone and voice-activated searching. Over lunch at the Google cafe, she told us where the science of Web searching is headed.
How does Google search now?
Google goes out to the Web and collects Web pages. Then we build an internal representation of them, and when a user types in a query this internal representation is used to quickly find the documents that contain these words. We have more than 1.3 billion in our index, which we completely update every 28 days.
For each word, we store all the documents that contain it. So, when you type in the query terms, we can just go to the words, and do an intersection of the lists -- find the documents that contain all these words. We've pre-done the search for each original term alone and stored all the answers. So if you type in the word "car" and the word "repair," we search the list for the word "repair" and the word "car." And we will input documents that contain both of them. Then we have to order them. But we don't only return those documents, we also return documents where other people point -- have a hyperlink -- to this page.
How does Google figure out the order?
A very important criterion is how many people link to you and how many people link to them. It's a recursive definition where your "quality" depends on the quality of links that point to you.
To order them, we look at the link structure. When we build the internal representation, we assign a number to each document that depends on its link structure. We then use this information to order the documents. The page-rank measure is based on the whole Web structure.
The results are ordered by a combination of what we think the quality is and also the query terms. Basically, do we think by looking at the document that it's on this topic? That's also what lots of our future work concentrates on: trying to understand better what documents are about, and also trying to understand better what the user queries are about. The problem is that most user queries are very short -- two or three words -- so it's hard to figure out what they mean, even if you're a human being. Did you see the queries in the lobby?
Yes. [In Google's lobby, a constantly scrolling list of queries projected on the wall behind the front desk shows what visitors to Google are searching for. A random sample when I visited: Chadwicks of Boston, Olympics archery, Ph.D. salary survey, upright scaffolds, World Cup luge.]
That's a filtered version, except that the filter doesn't work well in other languages. So we had people here from BMW, and they told me that there were some German queries that got through that shouldn't have.
[Note to self: Curse on Google only in foreign tongues.]
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